Electron-discharge device



Oct. 23, 1928. 1,688,991

P. SCHWERIN v ELECTRON DISCHARGE DEVI CE Filed Oct. 29, 1923 Av f I //7l//7/0/." I 1 40/ Jam arm.

Patented a. 23, 1928.

U N i T E 1.58. rust PAUL SCHWERIN', OF NEW YORK, N. Y., ASSIGIN'OR [ZO XR 'ESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEVJ YORK.

ELECTRON-DISCHARGE DEVICE.

Application filed fictober 29, 1923. Serial No. e71 248.

This invention relates to electron discharge devices and pertains more especially to vacuum tubes having three electrodes.

The object of the invention is to simplify the assembly of the electrodes in the I1121Illlfacture of the device.

This object is attained by making the grid and anode substantially trough shaped. This permits mounting the filament upon its support and subsequently disposing the other electrodes around the filament in operative relation thereto instead of first mounting the grid and anode and then threading the filament through them and attaching it to its supports. The grid and anode are preferably mounted in the tube so that the open portions thereof face the press of the tube. The sides of the grid project sulfieiently beyond the filament that it remains always in the field between the cathode and anode de spite sagging of the filament,

Referring now to the drawings, Fig. 1 discloses a vacuum tube constructed in accordance with the invention. Fig. 2 is a detail of the grid electrode before completion, and Figs. 3 and 4 are detail views of modified forms of the grid.

A glass bulb forms the enclosing vessel for the device and is compressed as at 11 to form a stem for the leading-in and supporting wires. The free ends of the leading-in wires 12 and 13 are relatively widely separated and support the opposite ends of a filamentary cathode 14:. The ends of the leading-in wire 15 and the supporting Wire 16 are attached to the opposite ends of a trough shaped grid electrode 17 which 1s disposed about the filament 14 so that it substantially surrounds the same. The ends of the leading-in wire 18 and the supporting Wire 19 are welded to projections 20 and 21 extending from the opposite ends of a trough shaped anode 22 which comprises a sheet metal stamping bent to the desired shape. The grid and anode are supported substan tially coaxially with the cathode having their open portions facing the stem or press 11.

The grid electrode 17 comprises, in effect, a series of U-shaped metallic members supported by longitudinal members. It may be composed, as shown in Figs. 1 and 2, of a wire frame 23 having one end 24 projecing beyond the side of the frame, and a cor responding projecting member 25 welded to the opposite end of the frame. Aseries of U-shaped cross wires 26 extend between the side members and are welded thereto. The grid is preferably made up in the form of a plane member and is then bent around a mandrel into a substantial trough shape. The projecting ends at and 25 are welded to the ends of the leading-inand supporting.

wires 15 and 16 to support the grid in operative relation to the filament.

The trough shape of the grid and anode simplifies materially the assembly of the electrodes since the filament 14 may first be strung between its supports and the grid 17 and anode 22 may be slipped over the filament and fastened in proper position. This obviates the delicate and tedious step of passing the filament through the grid and anode and attaching it to its supports. The grid and anode are of sufficient depth that the filament cannot sag below their edges when it expands upon being heated, or sags for any reason thereby maintaining the grid and anode substantially symmetrical with respect to the filament. This arrangement maintains an elficient relation of the electrodes at all times and insures that the field between the anode and cathode is efficiently controlled by the grid voltage.

Figs. 3 and 4: disclose modified forms ofgrid. In Fig. 3, a single length of wire 27 is bent to form a succession of U-shaped members connected by portions 29 and 30 of the wire so that a substantially trough shaped grid is provided. The ends of the wire 27 are extended beyond the edge of the grid proper to provide supporting connections to the leading-in wires. In Fig. 4, the grid 31 comprises a stamping from a flat sheet of metal. The finished grid comprises a pair of side members 32 connected by the plurality of U-shaped ribbons 33 which combine to form a substantially trough shaped grid. At opposite ends of the grid are provided projecting members 34 and 35 which may be welded to the supporting wires. Manufacture of'a grid, such as disclosed in Fig. 4, necessitates merely a blanking and bending operation and very materially reduces the labor involved in the manufacture of a grid since the need of any welding operations is entirely avoided.

What is claimed is:

1. In an electron discharge device, a press, pairs of lead-in wires sealed in said press, a straight filamentary cathode supported between one pair of lead-in Wires and lying at right angles to the axis of the press, a

v trough shaped grid electrode located parallel to and effectively surrounding said filament with its open side facing said press, said grid bein supported at its opposite ends b a pair of said lead-in Wires, and a trough s aped anode located parallel to and above said grid and filament and being supported at its opposite ends by a pair of said leadin Wires.

2. In an electron discharge device, a press, pairs of lead-in wires sealed in said press, a straight filamentary cathode supported between one pair of lead-in Wires and lying at right angles to the axis of the press, a grid electrode comprising a metal plate having portions cut out to provide a pair of longitudinal members and a pluralityof lateral members connected to said longitudinal members, said lateral members being-bowed intermediate their ends, said grid being located parallel to and over said filament and eil'ectively surrounding the same and being supported at its opposite ends by a pair of said lead-in Wires, and an anode comprising a sheet metal trough located parallel to and over said grid, said anode being supported at its opposite ends by a pair of said lead-in wires; V

In Witness whereof, I hereunto sub scribe my name this 22nd day of October PAUL SCHWERIN. 

